Self cleaning outsoles for shoes

ABSTRACT

This invention relates to shoe outsoles, for sport and street wear, which exhibit a resistance to the adherence of foreign material. Certain adherence modifying agents, which help resist the adherence of foreign material, can be either incorporated into materials from which a shoe&#39;s outsole or outer are formed, or applied as a coating thereto.

FIELD OF INVENTION

This invention relates to shoe outsoles, for sport and street wear,which exhibit a resistance to the adherence of foreign material. Thepresent invention relates to coating technology to reduce the adhesionof dirt and foreign material.

BACKGROUND DESCRIPTION

A problem with sports shoes in particular is that foreign material, suchas dirt and grass, adhere to the outsole. The accumulated effects ofthis build-up include increased weight, and decreased traction andperformance. This is particularly undesirable for players in competitiongames, though still is a significant problem during casual games orpractice. Any player who has spent countless hours cleaning soccer orrugby boots will appreciate any improvement which will reduce cleaningtime, or the need for extensive cleaning.

While this represents a significant problem for players of ball sports(e.g. soccer and rugby, etc.) the problem extends to other areas. Forinstance, golf is another sport where plant material and dirt adheringto shoes is a problem. This can be a particular problem in transmittingweeds between different courses. Tramping and hiking boots can alsosuffer an accumulated build-up of dirt and foreign material, increasingweight, reducing traction, and distributing plant and soil flora andfauna between different environments.

Biosecurity measures during international travel often target shoeswhich have been used for hiking, visiting farms, golfing, ball sportsetc. Any modifications which improve an outsole's resistance toaccumulating soil and plant matter will be of assistance in preparingshoes for international travel.

Other similar problems appear in farming, and in farm boots (includinggumboots and Wellington boots). Farm boots in wet weather tend toaccumulate mud, and become very heavy and slippery underfoot. Farm bootsalso stand in animal dung and other microbiologically active material.Reducing transmission from one area to another can be of greatsignificance. Reducing the amount of mud walked into the farm vehiclewould be widely welcomed as well.

As can be seen, there is a problem in a wide range of fields whereundesirable material is spread or transmitted from one area to anotherby being earned on the soles of shoes. Accordingly there is a need foran effective solution to such problems, such as an outsole which isresistant to the adherence of foreign material.

The applicant has also investigated various techniques for producingsoiling resistant surfaces, and particularly techniques similar to thatused by the lotus leaf in nature, and this is the subject of anotherpatent application. The term ‘lotus-effect’ refers to the self-cleaningproperties of lotus leaves. When rainwater dropped to the hydrophobicsurface of the leaves of a lotus, it forms into water beads due to theeffect of surface tension, i.e., the contact angle between the surfaceof the leaves of the lotus and water will be over 140 [deg.], and thewater beads will roll away from the leaves when shaking the leaves.Further, rolling water beads carry dust from the surface of the leaves.Therefore, the surface of the leaves is maintained clean and dry after aheavy rain. The chemical structure of the wax crystal is hydrophobic.When water contacts the surface of a lotus leaf, it forms into waterbeads due to the effect of surface tension. Due to the effect of thefine protruding epidermal cell structure, the contact area between waterand the surface of the leaf is minimized and the contact angle betweenwater and the surface of the leaf is maximized, enhancing the effect ofhydrophobicity, and lowering the adhesion power of solid matter to thesurface of the leaf. The nanometered fine structure also plays animportant role in self-cleaning. However, rolling water beads on thehydrophobic smooth surfaces of other plants or man-made products cannotcause water beads to carry solid matter from the surfaces. Lotus leavesbecome clean and fresh when washed by a heavy rain

In related examples United States (US) patent US2001037876 describes anevaporator having a heatable heat exchange surface, which has aself-cleaning micro-structured surface with elevations and depressions.In addition US patent US2004081764 discloses an antisoiling hard coatedfilm comprising a substantially transparent substrate, a hard coat layercomprising inorganic oxide particles dispersed in a binder matrix, andan antisoiling layer comprising a perfluoropolyether.

Alternative attempts at achieving this effect on shoe outsoles are citedin Adidas patents DE3521141 and JP8252102. These patents both suggest amechanical means for achieving this effect.

Ideally the industry requires effective techniques for reducing theadherence of foreign material on shoe outsoles, and which is ideallyrelatively easy to implement.

It is therefore an object of the present invention to provide animproved outsole whose outer surface exhibits a resistance to theadherence of soil or plant matter likely to be encountered during normaluse of a shoe.

At the very least, it is an object of the present invention to providethe public with a useful choice.

Aspects of the present invention will be described by way of exampleonly and with reference to the ensuing description.

GENERAL DESCRIPTION OF THE INVENTION

According to one aspect of the present invention there is provided ashoe outsole or outer, at least of a portion of the outer surface ofwhich comprises a resin into which is incorporated at least oneadherence modifying component.

According to another aspect of the present invention there is provided ashoe outsole or outer, substantially as described above, in which anadherence modifying component comprises a member of the groupcomprising: fluorocarbons, silicones, siloxanes, and polysiloxanes,modified polyacrylates, modified polysiloxanes, and acrylates.

According to another aspect of the present invention there is provided ashoe outsole or outer, substantially as described above, in which anadherence modifying component comprises a particulate material, theparticulate material being of a member of the group comprising:compounds based on PTFE, polyethylene, polypropylene, and hydrophobicfumed silica.

According to another aspect of the present invention there is provided ashoe outsole or outer, substantially as described above, in which anadherence modifying component comprises a particulate material, theparticulate material being of a member of the group comprising:functionally modified PTFE compounds, and functionally modifiedpolyethylenes, functionally modified polypropylenes.

According to another aspect of the present invention there is provided ashoe outsole or outer, substantially as described above, in which a saidparticulate material has an average particle diameter within the rangeof 0.001 nanometres to 100 microns inclusive.

According to another aspect of the present invention there is provided ashoe outsole or outer, substantially as described above, in which theproportion of adherence modifying component(s) present is based on aloading range of 0.5 to 20% (inclusive) by weight.

According to another aspect of the present invention there is provided ashoe outsole or outer, substantially as described above, which theproportion of adherence modifying component(s) present is based on aloading range of 5 to 15% (inclusive) by weight.

According to another aspect of the present invention there is provided ashoe outsole or outer, substantially as described above, in which anadherence modifying component when incorporated into said resin providesa low surface energy, which is below 50 dynes/cm.

According to another aspect of the present invention there is provided ashoe outsole or outer, substantially as described above, in which anadherence modifying component when incorporated into said resin providesa low surface energy, which is below 35 dynes/cm.

According to another aspect of the present invention there is provided ashoe outsole or outer, substantially as described above, in which anadherence modifying component when incorporated into said resin providesa low surface energy, which is below 20 dynes/cm.

According to another aspect of the present invention there is provided ashoe outsole or outer, substantially as described above, in which saidresin comprises a cross-linkable resin, a self cross-linking resin, or acompatible film-forming binders.

According to another aspect of the present invention there is provided ashoe outsole or outer, substantially as described above, in which theresin is an acrylic or polyurethane resin.

According to another aspect of the present invention there is provided ashoe outsole or outer, substantially as described above, in which theresin includes a cross-linking agent.

According to another aspect of the present invention there is provided ashoe outsole or outer, substantially as described above, in which aresin with adherence modifying component is present as a coating on theoutsole or outer.

According to another aspect of the present invention there is provided ashoe outsole or outer, substantially as described above, in which theresin with adherence modifying component(s) is applied as a coating toan outsole or outer by a method comprising: spraying, dipping, plasmacoating, corona discharge, brushing, or rolling.

According to another aspect of the present invention there is provided ashoe outsole or outer, substantially as described above, which theoutsole or outer to which the coating is applied is of a TPU(thermoplastic polyurethane).

According to another aspect of the present invention there is provided ashoe outsole or outer, substantially as described above, in which thecoating applied to the outsole or outer is based on a water basedsolvent system.

According to another aspect of the present invention there is provided ashoe outsole or outer, substantially as described above, in which thecoating is applied to a thermoplastic outsole or outer.

According to another aspect of the present invention there is provided ashoe outsole or outer, substantially as described above, in which theoutsole, or a portion thereof, is formed of a resin incorporating one ormore adherence modifying components.

According to another aspect of the present invention there is provided ashoe which possessing either or both of an outsole or outer of which atleast a portion is substantially as described above.

According to another aspect of the present invention there is provided ashoe, substantially as described above, which falls into one or more ofthe following categories: soccer boot, rugby boot, shoe or boot for ballsports, shoe for court sports (e.g. tennis, badminton, etc.), golf shoe,athletic shoe, cross-trainer, sporting shoe, hiking or tramping boot,walking shoe, and climbing shoe.

According to another aspect of the present invention there is provided amethod for modifying the resistance of at least part of an outsole tothe adhesion of foreign material, said method comprising the applicationof a coating of a resin including one or more adherence modifyingcomponents to produce an outsole or outer substantially as describedabove.

Definitions

The term ‘shoe’ is intended to include ‘boots’ and other footwear withinthis specification. Sometimes the term ‘boot’ will be used as it may becommonly used within the industry in the context being talked about, butfor the purpose of determining the scope of the invention it shall fallwithin the definition of ‘shoe’—for instance it is common to refer to‘soccer boots’ rather than ‘soccer shoes’, though ‘soccer boots’ willfall within the definition of a ‘shoe’. Equally the present invention isequally applicable to business and fashion shoes and boots. Again, forthe purpose of determining the scope of this invention, both categories(boots and shoes) will fall within the term ‘shoe’. ‘Sandals’ are alsointended to fall within the definition of ‘shoe’.

The term ‘outsole’ generally applies to the outer sole portion of ashoe, though radical shoe designs may blur where the sole starts andend. Generally this will refer to the sole portion and extensions (intothe upper) thereof.

The term ‘shoe outer’ generally applies to outer portions of a shoewhich are not the outsole.

The present invention relates a soil-resistant and/or self-cleaningoutsole or outer for use on shoes. The outsole or outer may besynthetic, of natural products, or a mixture. It is intended that thepresent invention can be used on a variety of shoes, comprising (forinstance) but not restricted to: soccer boots, rugby boots, boots andshoes for ball sports, golf shoes, tramping and hiking shoes and boots,cross-trainers, shoes for court sports, sandals, business and fashionfootwear, walking shoes, running shoes, street shoes, gumboots, farmboots, safety boots and shoes, shoes and boots for in clean areas (e.g.food processing, dairy and meat industries, etc.), and shoes for use inbiohazard areas. For simplicity of description however, the remainingspecification will refer primarily to sports shoes such as soccer boots.It is envisaged that application to other shoes and boots will bereadily apparent to the skilled reader in light of the description givenherein.

Improvements according to the present invention can be made according totwo primary techniques 1) surface treatment of the outsole or an outerpart of the shoe, and 2) additives combined with the raw material of theoutsole or shoe's outer. These will be discussed individually asfollows. For simplicity the description refers to outsoles inparticular, though it should be appreciated that coating and surfacetreatments can also be applied in many case to other parts of the shoe'souter, and especially the upper (or portions thereof).

1. Surface Treatment of the Outsole Or Outer

Surface treatment coatings applied to the present invention typicallyinclude adherence modifying components, typically low surface energymaterials, these components comprising (but not restricted to)fluorocarbons, silicones, siloxanes, polysiloxanes, and particulates.The particulates may, for instance, be waxes based on PTFE,polyethylene, polypropylene, hydrophobic fumed silica, etc. Theseparticles can range in diameter, are not necessarily spherical, and arepreferably within an inclusive size range of 0.001 nanometres to 100microns (average particle diameter). Furthermore, these particulates canbe chemically modified to achieve better compatibility and fixation, andconsequently performance, e.g. hydroxy functional PTFE. All thematerials quoted provide a low surface energy, which preferably shouldbe below 50 dynes/cm, more optimally below 35 dynes/cm and ultimatelybelow 25 dynes/cm in order to gain the desired effect. Combinations ofthese products are also a possibility, and within the scope of thepresent invention.

The surface treatment coating films are formed from a film formingresin, comprising cross-linkable (which include self cross-linkingvarieties) resins (generally of an acrylic or polyurethane nature), orsuitable film-forming binders, having the above mentioned modifyingcomponents dispersed therein. Such films appear to exhibit improvedanti-soiling characteristics, compared to films from cross-linkableresins that do not contain such materials.

This is particularly advantageous with regard to outsole and outersurfaces that need to remain free of contamination during use.

It has been found that 0.5 to 20% (inclusive) is a typical loading rangeof the adherence modifying component (by weight) within the surfacetreatment coating, with a range of between 5 to 15% (inclusive) beingpreferred.

A process is provided for making a film-forming composition (for use asa surface treatment coating) containing these materials dispersed in across-linkable resin. The process comprises adding the material to amedium (generally a film forming resin), being selected from (but notlimited to) the group of film forming resins listed above. Then thematerial(s) and medium are mixed to form a dispersion, which may requirehigh sheer mixing with the aid of a suitable auxiliary dispersant. Nextthis coating composition is applied to the outsole surface (e.g. a TPU(Thermoplastic PolyUrethane) resin outsole) by a suitable means of anapplication method which can control the specific amounts applied. Suchequipment may be, but is not limited to, spraying equipment, dippingequipment, plasma coating techniques, corona discharge methods, etc.

As a result the coating is cured, dependent upon the resin type used,which can include (but is not limited to) moisture curing, heat curing,UV curing, and radiation curing, etc. Furthermore the coating can bereinforced (particularly to gain added hydrolytic stability) by the useof self cross-linking resins or the inclusion of cross linkers such aspolyaziridines, polyisocyanates, etc., though may include other crosslinking agents.

Various solvent systems may be used, and may be chosen to reflect thenature of the substrate to which it is applied. Aqueous based solventsystems and components may be used, and these may be more appropriatefor thermoplastic materials.

Once cured a durable anti-soiling film is formed upon the surface of theoutsole. This achieves a hybridic complex of resin and material,offering permanent self-cleaning, hydrophobic, oleophobic, andanti-adhesive effects.

2. Additives Combined With the Outsole Or Outer's Raw Material

Outsoles (and outer portions) of the present invention can be formedincluding outsole modifying components, these comprising fluorocarbons,silicones, siloxanes. polysiloxanes, and particulates. The particulatesmay, for instance, be waxes based on PTFE, polyethylene, polypropylene,hydrophobic fumed silica, etc. These particles can range in diameter,are not necessarily spherical, and are preferably within an inclusivesize range of 0.001 nanometres to 100 microns (average particlediameter). Furthermore, these particulates can be chemically modified toachieve better compatibility and fixation, and consequently performance,e.g. hydroxy functional PTFE. All the materials quoted provide a lowsurface energy, which preferably should be below 50 dynes, moreoptimally below 35 dyes and ultimately below 25 dynes in order to gainthe necessary effect. Combinations of these products are also apossibility.

An outsole or outer modifying component is mixed with a TPU(Thermoplastic PolyUrethane) resin before the moulding process begins.Once the TPU mix is injected into the mould, it will form anequilibrated structure throughout, with substantially permanentanti-soiling properties contained throughout the outsole, and where theeffect is constantly replenished with wear. These improved outsoles andouters exhibit improved anti-soiling characteristics, compared tooutsoles that do not contain such materials.

This has the potential to be particularly advantageous with regard tooutsole and outer surfaces that need to remain free of contaminationduring use.

DESCRIPTION OF PREFERRED EMBODIMENT

With reference to the drawings, and by way of example only, preferredembodiments of the present invention will now be described.

1. Surface Treatment of the Outsole Or Outer Example 1

The following formulation is made:

78% Solvent based polyurethane

10% Solvent based polyisocyanate

10% modified acrylate e.g. NLC Additive SS1 (NLC, UK)

2% Flow Agent

The above mixture may require high speed shear stirring to ensureadequate dispersion. Anti-foaming agent may be required and added asnecessary.

The commercial preparation NLC Additive SS1 from NLC (Northants LeatherChemicals) in the UK is correctly described as an OH-functional siliconemodified polyacrylate. The product is now marketed as “Norsol AD50” bythe same company.

The mixture is then applied by a spraying, with the application of from0.05 to 250 gft⁻², though more preferably in the range 7-30 gft⁻²inclusive. This is then heat cured until properly cured. For thepreferred coating range, this may be for 3 minutes at a temperature of125° C., and allowed to cure for a further 48 hours at room temperaturebefore any sort of laboratory testing.

The outsole can then be applied to the upper. In addition the outsole ofcompleted shoes can also be treated in this manner. Shoe outers (e.g.uppers) may be coated during shoe manufacture or after attachment of theoutsole.

Example 2

The following formulation is made:

78% Solvent based polyurethane

10% Solvent based polyisocyanate

10% Solvent based fluorocarbon e.g. NLC Additive SS3 (NLC, UK)

2% Flow Agent

The above mixture may require high speed shear stirring to ensureadequate dispersion. Anti-foaming agent may be required and added asnecessary.

The mixture is then applied by a spraying, with the application of from0.05 to 250 gft⁻², though more preferably in the range 7-30 gft⁻²inclusive. This is then heat cured until properly cured. For thepreferred coating range, this may be for 3 minutes at a temperature of125° C., and allowed to cure for a further 48 hours at room temperaturebefore any sort of laboratory testing.

The outsole can then be applied to the upper. In addition the outsole ofcompleted shoes can also be treated in this manner. Shoe outers (e.g.uppers) may be coated during shoe manufacture or after attachment of theoutsole.

2. Additives Combined With the Outsole Raw Material Example 3

The following formulation is made:

88% TPU resin

10%, Hydrophobic fumed silica e.g. NLC Additive SS2 (NLC, UK)

2% Dispersing Agent

The mixture is then injected into an outsole mould for thermoforming.

The outsole can then be applied to the upper. In addition the outsole ofcompleted shoes can also be treated in this manner. Shoe outers (e.g.uppers) may be coated during shoe manufacture or after attachment of theoutsole.

This technique offers the potentially realisable added benefit ofenhanced durability due to the effect being locked within the outsole orouter material and constantly offering benefits as the outsole or outerwears.

Some outsoles are manufactured from injected portions of differentresins/plastics (sometimes visible as areas of different colour). Resinsfrom different areas may be formulated to include additives according tothe present invention—they may be also formulated differently fromdifferent areas.

Aspects of the present invention have been described by way of exampleonly and it should be appreciated that modifications and additions maybe made thereto without departing from the spirit or scope of thepresent invention as defined in the appended claims.

It should also be understood that the term “comprise” where used hereinis not to be considered to be used in a limiting sense. Accordingly,‘comprise’ does not represent nor define an exclusive set of items, butincludes the possibility of other components and items being added tothe list.

This specification is also based on the understanding of the inventorregarding the prior art. The prior art description should not beregarded as being authoritative disclosure on the true state of theprior art but rather as referencing considerations brought to the mindand attention of the inventor when developing this invention.

1-24. (canceled)
 25. A shoe outsole or outer, at least of a portion ofthe outer surface of which comprises a resin into which is incorporatedat least one adherence modifying component which comprises a member ofthe group comprising: fluorocarbons, silicones, siloxanes, andpolysiloxanes, modified polyacrylates, modified polysiloxanes, andacrylates.
 26. A shoe outsole or outer, as claimed in claim 25 in whichan adherence modifying component comprises an OH-functional siliconemodified polyacrylate.
 27. A shoe outsole or outer, as claimed in eitherclaim 1 which includes a particulate material, the particulate materialbeing formed of a member of the group comprising:polytetrafluoroethylene, polyethylene, polypropylene, hydrophobic fumedsilica, functionally modified PTFE compounds, functionally modifiedpolyethylenes, and functionally modified polypropylenes.
 28. A shoeoutsole or outer, as claimed in claim 27, in which a said particulatematerial has an average particle diameter within the range of 0.001nanometres to 100 microns inclusive.
 29. A shoe outsole or outer, asclaimed in claim 25, in which the proportion of adherence modifyingcomponent(s) present in the resin is within a loading range of 0.5 to20% (inclusive) by weight.
 30. A shoe outsole or outer, as claimed inclaim 25 in which the proportion of adherence modifying component(s)present in the resin is within a loading range of 5 to 15% (inclusive)by weight.
 31. A shoe outsole or outer, as claimed in claim 25 in whicha said resin with adherence modifying component has a surface energywhich is below 50 dynes/cm.
 32. A shoe outsole or outer, as claimed inclaim 25 in which a said resin with adherence modifying component has asurface energy below 25 dynes/cm.
 33. A shoe outsole or outer, asclaimed in claim 25 in which said resin comprises at least one of across-linkable resin, a self cross-linking resin, and a compatiblefilm-forming binder.
 34. A shoe outsole or outer, as claimed in claim 33in which the resin is an acrylic or polyurethane resin.
 35. A shoeoutsole or outer, as claimed in claim 34 in which the resin includes across-linking agent.
 36. A shoe outsole or outer, as claimed in claim 25in which a said resin with adherence modifying component is present as acoating on the outsole or outer.
 37. A shoe outsole or outer, as claimedin claim 36 in which the resin with adherence modifying component(s) isapplied as a coating to an outsole or outer by a method comprising:spraying, dipping, plasma coating, corona discharge, brushing, orrolling.
 38. A shoe outsole or outer, as claimed in claim 36 in whichthe outsole or outer to which the coating is applied is of a TPU(thermoplastic polyurethane).
 39. A shoe outsole or outer, as claimed inclaim 36 in which the coating applied to the outsole or outer is basedon a water based solvent system.
 40. A shoe outsole or outer, as claimedin claim 39 in which the coating is applied to a thermoplastic outsoleor outer.
 41. A shoe outsole or outer, as claimed in claim 25 in whichthe outsole, or a portion thereof, is formed of a resin incorporatingone or more adherence modifying components.
 42. A shoe which possessingeither or both of an outsole or outer of which at least a portionthereof comprises a shoe outsole or outer as claimed in claim
 25. 43. Ashoe as claimed in claim 42 which falls into one or more of thefollowing categories: soccer boot, rugby boot, shoe or boot for ballsports, shoe for court sports, golf shoe, athletic shoe, cross-trainer,sporting shoe, hiking or tramping boot, walking shoe, and climbing shoe.44. A method for modifying the resistance of at least part of an outsoleto the adhesion of foreign material, said method comprising theapplication of a coating of a resin including one or more adherencemodifying components to produce an outsole or outer according to claim25.